What is it that makes creases form when you wash or wear clothes and how and why does ironing remove them?
The interactions between polymer molecules inside the individual threads of woven clothing determine if it is prone to creasing.
In cotton and linen, adjacent cellulose molecules can cross-link to form weak, reversible links known as hydrogen bonds. These links can be broken and reformed under pressure, in the presence of heat and moisture – whether this is provided by the human body while being worn, by a washing machine or by ironing. The cellulose in the cloth is then temporarily held in its latest shape until the bonds are rebroken during washing and then reformed (minus creases) as the cellulose in the threads is pressed flat by the heat and moisture of ironing, until dry.
Synthetic polymers like nylon and polyester contain few or no hydrogen bonds and are much less prone to creasing. “Easy iron” cotton clothing has been permanently cross-linked by a chemical treatment, which makes the cloth resist creasing.
The interactions between polymer molecules inside the threads of woven clothing determine if it is prone to creasing
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